This application relates to a method of improving images which have been captured over a very long range, and through the atmosphere.
Various image capture applications are known, and include capturing images of an area of interest from a very high altitude, such as from an airborne surveillance vehicle.
Long atmospheric path imaging is a challenge. As an example, one feature in an image may be captured through relatively calm air, whereas an adjacent feature may be through turbulent atmosphere. The turbulence can affect the quality of the image, and can lead to various modifications in the captured image that can challenge the reconstruction of the image.
The image can become diffuse, or a feature can simply be bent.
FIG. 1A shows an example wherein an aircraft 20 has an image capture device (a camera) 22 capturing images associated with the ground 24. The distance d from the ground 24 to the aircraft 20, is relatively great.
One point of interest 26 is associated with atmosphere having turbulence, shown schematically at 30. Another point of interest 28 may have no turbulence. Thus, the image 34 extending from the point of interest 28 is relatively undisturbed. On the other hand, the turbulence 30 can change the true image 31 of the area of interest 26 such that it is bent as shown schematically at 32.
Another area of interest 36 may have diffusion as shown at 38 by the time it passes through the distance d.
FIG. 1B shows one example of an image from an area of interest 36 which results in several repeated images 136 spaced about the actual center of the area of interest 36. This can result from turbulence, or simple diffusion of light as explained above with FIG. 1A.
FIG. 1C shows a light point 137 which is diffused to a large area 139. All of these raise challenges with regard to reconstructing an accurate image from an aircraft 20, or other application of capturing an image over a relatively great distance.
As also shown in FIG. 1A, the image capture device 22 may capture an image in a direction X which is not perpendicular to the ground 24. The direction X is shown to be spaced by an angle ζ.